With the mass application of the intelligent optical network technology, the construction and development of a transport network have been developed from the single hardware transport technology to a comprehensive transport technology which integrates the network management technology, the control technology and hardware technology. With the help of a control plane of the intelligent optical network, the reliability of the network is improved and new bandwidth services, such as optical virtual private network (OVPN) and bandwidth on demand (BoD), can be provided quickly as well, thereby bringing improved efficiency and decreased cost for operation and maintenance of the network.
However, as types of the services are more and more various, the proportion of bandwidth, especially consumed by packet services, is higher and higher, and service granularity is more and more large as well. A synchronous digital hierarchy (SDH)/synchronous optical network (SONET) device which is designed originally for voice bearing has not well satisfied the development of future application, thus, the intelligent optical network has an unstoppable tendency to evolve from a SDH network to an optical transport network.
Transmission of large-granularity services challenges service grooming ability of a wavelength division multiplexing (WDM) node. Recently, a great breakthrough has been obtained in the reconfigurable optical add drop multiplexer (ROADM) technology, and the micro electromechanical system (MEMS)-based technology, such as wavelength selective switch (WSS), solves the problem of reconfigurability of an optical wavelength such that flexible up- and down-conversion and punch-through of the optical wavelength can be implemented to a certain extent. Furthermore, the ROADM is not required to use optical-electrical-optical (OEO) conversion in transmitting a signal from one network to another such that the cost of optical-electrical-optical conversion can be eliminated. Many factories in the industry have provided a WDM system with optical layer reconfigurable properties. In addition, in view of advantages of the OTN over the wavelength division system in terms of a definition of the node and end-to-end management, the OTN begins to appear on commercial transmission devices. Consequently, dynamic control requirements for wavelength/sub-wavelength are brought, as with an automatically switched optical network (ASON) for an add/drop multiplexer (ADM) of the SDH/SONET.
However, it is because the ROADM is not required to use the OEO conversion, only direction of the wavelength can be re-assigned and wavelength conversion cannot be performed such that it is not non-blocking completely in the wavelength conversion. Although an OEO conversion device can be introduced in the ROADM to implement the wavelength conversion, completely non-blocking wavelength conversion cannot be implemented due to the limitation of the cost and conversion capacity of the OEO devices.
Currently, there are two processing methods for block information described above. The first method is to notify each node of the block information by expending routing flood information and perform route computation taking the block information into consideration in order to ensure that the calculated route is interchangeable at each node. The success rate of setting up a connection between routes which is calculated by this method is high, but a lot of flood information is required to be added. The second method is not to flood the block information and not to reserve specific resources during forward signaling when the connection is established, but to give an available resource range and finally select resources to be used according to the previously given range at a target node. This method does not need to add additional flood information, but the success rate of setting up the connection between the calculated routes is low.